What do we know about the 9" diameter round Mobiloil-Gargoyle sign that shows up from time to time.Looks kind of like a pump plate and has the gargoyle on it.This is the variety that also has a date at the bottom, 11-39 I think. I've seen these at swap meets and on the 'net.They aren't the usual 12" diameter re-pop that you see all the time and the rivets look good.Any thoughts?